Basic concepts and properties of new generation ammonia synthesis catalysts for industrial use

摘要

Highly active ruthenium catalysts (the second generation ammonia synthesis catalysts) are being usedfor a new ammonia plant.One problem to be overcome forthe ruthenium catalysts is the strong hydrogen poisoning (Ru-CsOH/MgO as a typical example shown in this study).The authors have found that ruthenium catalysts promoted with rare earth oxides such as Ru/CeO_2 can be free from the strong hydrogen poisoning.Mainly these two catalysts were studied under elevated pressures or various hydrogen-nitrogen pressure ratios and compared with the behaviors of an iron catalyst.It is proposed that an ammonia-susceptible catalyst (Ru/CeO_2) should be placed at the front-stream position and a hydrogen-susceptible catalyst (Ru-CsOH/MgO) should be placed at the down-stream position in the reactor.